Our present computer systems are ridiculously "deterministic" and clean, in comparison to the crud behind biological organisms (evolution, over the last few billion years, didn't strictly care about behind-the-scenes "how?").
We demonstrably have a decent grip on on the former (sure, we don't do many things in computers in the most elegant way, but that's about something else - market dynamics; also the "indifferent evolution" taking hold, really), while in the latter - tons of big, unanswered dilemmas (heck, we don't even really know why we age). Supposedly, XXI will only be the century of biology / biochemistry.